


Rainbow Kryptonite

by ThatLesbianFangirl



Category: Supergirl (TV 2015)
Genre: Canon Compliant, F/F, Humor, You Decide, but also kinda not???, idk man, kara is a doofus gaylien, kind of a crack fic
Language: English
Status: Completed
Published: 2017-10-05
Updated: 2017-10-05
Packaged: 2019-01-09 10:14:34
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,570
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12274332
Author URL: https://archiveofourown.org/users/ThatLesbianFangirl/pseuds/ThatLesbianFangirl
Summary: Alex creates a completely fake, but realistic-looking rainbow colored kryptonite in an attempt to make her oblivious Kryptonian sister realize that she’s in love with Lena Luthor.





	Rainbow Kryptonite

**Author's Note:**

> Inspired by this tumblr post:  
> https://tht-lesbian-fangirl.tumblr.com/post/165884020239/thefingerfuckingfemalefury-brookietf
> 
> And thanks to @katiemcgarth for telling me to actually give it a shot :)

“So last night, I ate dinner with Lena in L Corp and she…” Blah blah blahhh.

 

Alex’s patience had finally worn thin. All Kara ever talked about was “Lena _this_ ” and “Lena _that_.” Lena, Lena, Lena. Lena was great, like very great. She’s wonderful in fact. And the discussing her so frequently wouldn’t be so painful if Kara at least acknowledged why she only wanted to ramble on about the Luthor. At first, Kara’s display of faith and attachment to Lena seemed abnormally friendly, but adorable. Yet after over a goddamn year of her obsessive chatter paired with exaggerated insistence that their relationship remained purely platonic, the older, out and proud Danvers sister wanted to combust.

 

When it seemed like Kara finished her rant, Alex spoke, “You certainly spend a lot of time with Lena.”

 

“Yeah, she’s amazing! I’m so lucky to have a friend like her,” Kara gushed.

 

“Mmhmm,” Alex grumbled and pulled out her notepad to draw another tick mark in the upper right section. A total of eight tick marks that represented how many times this week Kara had specifically referred to Lena as a friend. And it was only Tuesday afternoon.

 

Kara took a deep breath in and smiled at Alex on the exhale, “Well, I better head back to CatCo. Snapper doesn’t like it when I take extra long lunch breaks. Just call me if ya need Supergirl again.”

 

Alex smiled, “Will do.”

 

“And say hi to Maggie for me,” Kara gave Alex’s hand a light squeeze, then shot up into the air.

 

Alex watched her little sister disappear into the clouds, then packed up the DEO gear and made her way home. As she walked the couple blocks down to her apartment, Alex’s eyes trailed upwards to catch a glimpse of the impressive L Corp building. She chewed the inside of her cheek, ruminating on Kara’s aggravating denseness. By the time Alex stepped through her apartment door, pure frustration burst from her mouth.

 

“Maggie I can’t do this anymore, I can’t take it another day. Kara’s driving me INSANE. I–I don’t understand what goes through her brain. Clearly, all she thinks about is Lena, but she refuses to put two and two together,” Alex spewed, stomping into their living room.

 

“Hey, Danvers, it’s alright. Just give her some time,” Maggie chuckled, then pat beside her on the couch, motioning for Alex to join her.

 

“Some time? Babe. It’s been over a year. How much time does she need?”

 

Maggie pursed her lips, “Hey, that’s not fair. How many years did it take you to realize you liked women?”

 

“But this is completely different. When I met you, I knew–no, I _felt_ something different,” Alex shook her head, “Kara’s never acted like this before. Maybe a bit when she crushed on James, but never to this extent.”

 

“You can’t force your sister out of the closet.”

 

“Of course not,” Alex agreed. Then a mischievous grin spread across her face as a brilliant idea came to mind, “But I _could_ give her a gentle nudge…”

 

“Whatever you’re thinking Danvers, stop thinking it,” Maggie commanded.

 

Yet it was too late, Alex’s headstrong and stubborn personality took the reins, determined to complete her plan. She sped out of the apartment and made her way back to the DEO building. Bursting through the doors, she confidently strode towards Winn’s desk.

 

“Winn,” Alex boomed, “I need your help with something!”

 

At the sound of her voice, Winn nearly jumped out of his chair, “Uh, yes ma’a–Agent Ale–Danvers. Erm. Agent Danvers.”

 

Alex crossed her arms, “Seriously?”

 

“Hey, you used your scary voice,” Winn defended, shooting her a pair of puppy-dog eyes.

 

Alex sighed, “Whatever, I need your help and if you breath a word of this to _anyone_ I’ll–”

 

“You’ll kill me before a rogue alien can,” he waved his hand dismissively, “I know, I know. So, what can I do for you today?”

 

“You’re brilliant with styling materials, textures, and colors, right? We’ve all seen your super suits and gadgets,” the impish smile from only minutes ago returned to Alex’s face, “Well today you’re going to create something extra special.”

 

…

 

“Supergirl, come in,” Alex spoke into her earpiece at precisely 8:00 pm that same Tuesday.

 

“What’s up, Alex?” Kara answered in her usual, peppy voice.

 

Alex cleared her throat, “Winn picked up unfamiliar radiation signals from the abandoned warehouse near the pier. Can you meet me here to check it out?”

 

“Yeah, I’m on my way over right now. See you soon!”

 

And sure enough, within minutes Supergirl touched down next to Alex in front of the warehouse.

 

Alex nodded, “Thanks for coming. The signal came from the center of the building, but there seems to be life force movement inside.”

 

“So we don’t know what to expect?”

 

“Right,” Alex lied.

 

Kara cautiously approached the padlocked door, with Alex on her heels. As the sisters made their way through the dismal warehouse, Kara’s pace slowed.

 

“Alex...I think I feel something.”

 

“Yeah?” Alex feigned curiosity, trying to hide her excitement, “Let’s keep moving. We’re almost there.”

 

“Okay,” Kara squared her shoulders and marched into the next room.

 

It was pitch-black, with exception to an object glowing in the center of the room, giving off light so faint that only the cobwebs near it could be seen. Winn’s masterpiece. It was a cluster of crystals that he had colored rainbow and then glued together with epoxy gel. An incredibly tiny kryptonite emitter, one similar to the emitters used in the green kryptonite-lined DEO training room, laid in the very center of the fake rainbow crystal, causing it to glow. The amount of kryptonite Alex and Winn used was so minimal that Kara would barely feel it – she wouldn’t feel uncomfortable, but just enough to be brought down to normal strength.

 

Kara’s eyes dramatically widened in shock and fear, “Is that–”

 

“Kryptonite,” Alex confirmed.

 

“But it’s not green,” Kara’s brow furrowed.

 

“Neither was the silver kryptonite that Rhea once used on Superman This must be a different type and I’ll take it back to the DEO lab to see what effects it causes. Especially since you’ve been exposed to it.”

 

Kara clenched her jaw, “Let me know immediately when you find out. I’ll fly a lap around the city to look for an suspicious activity. We need to find out where this came from.”

 

“Yeah, definitely do that while I analyze the kryptonite,” Alex agreed and then thought, ‘ _Great, that will keep her busy while I figure out exactly what to say about the fake rainbow kryptonite.’_

 

Kara shuffled out of the warehouse and once she had enough distance between herself and the “kryptonite,” Supergirl leapt into the crisp night sky. Certain that she remained out of eyesight, Alex casually plucked the fake space rock up from the floor and shoved it into her pocket. The the benevolently mischievous Danvers sister, drove to the DEO for the third time that day, all the while chuckling to herself.

 

Alex paced played a zombie shooter game on her phone for half an hour to keep busy, then texted Kara around 8:50 pm: _Hey Kar, I analyzed the rainbow kryptonite. I think we need to talk about the effects. Please come back to the DEO asap._

 

Not a minute later, a loud thud echoed from the DEO control room. Clearly Kara was eager to hear what Alex “learned.” Alex took a couple deep breathes, made sure her poker face remained neutral, and stepped into the main lobby.

 

“Okay, don’t sugarcoat it. Just tell me what this rainbow kryptonite did to me,” Kara nervously said.

 

“Did I hear that correctly?” J’onn asked, walking over. Shit. Alex thought he’d already gone home for the night. “Umm I’m so sure there’s such a thing as rainbo––Ooof.” Alex jabbed J’onn in the side to get him to stop talking.

 

He shot her an incredulous look, so Alex, knowing that J’onn could read her mind, thought “ _Please just go with it. It’s for her own good._ ” When his skeptical expression didn’t falter, Alex added, “ _Fine, I promise I’ll tell her after a couple days._ ”

 

J’onn rolled his eyes at Alex, but pretended to be concerned, “So, what exactly did this rainbow kryptonite do to Supergirl?”

 

Alex dug her nails into the palm of her hand to keep a straight face, “Well, you see, it’s actually quite interesting. Something we’ve never seen before.”

 

“Alex just tell me!” Kara wailed.

 

“Alright, alright.” God, Alex almost lost her cool. Good thing she never wanted to be an actress. “Apparently, this type of kryptonite has more of an...emotionally altering effect. The ionic compounds I found suggest that it’s capable of causing gay impulses.”

 

Kara cast a doubtful look, “Alex that sounds ridiculous.”

 

“I would agree with that sentiment,” J’onn grunted, then walked away, no longer wanting to be a part of Alex’s wild antics.

 

“Kara, I know it sounds crazy, but that’s what the scientific algorithms say.”

 

Kara started walking towards the lab, “Okay well let me see the charts.”

 

“You can’t!” Alex jumped in front of her, “Umm because the charts are in a room with the kryptonite cracked open. You can’t be exposed to such a–”

 

“Whatever,” Kara shook her head and walked towards the DEO’s exit, “It’s been a long day and the streets sound pretty silent. I’m going home, do you want a lift?”

 

Alex slowly exhaled, “I’m good, I’ve got my car. And hey, if you start feeling any of the effects, let me know.”

 

Kara snorted, “I sincerely doubt I will, but okay Alex.”

 

…

 

But at 2:00 pm the next day, Alex received a frantic call, “Hey Kara, what’s u–”

 

“HelpIthinkIaccidentallyaskedLenaonadate!!!” Kara spoke so fast that her gibberish may as well have been Kryptonian.

 

“Slow down, what did you say?”

 

Kara spazzed out into the phone, “Oh Rao Alex, I kind of just blurted it out!”

 

“Blurted _what_ out?” Alex inquired, worried that Kara had told yet another person about her secret identity.

 

Yet, Kara’s answer completely surprised Alex. “The rainbow kryptonite made me ask Lena on a date! A REAL DATE!!” Kara shrieked.

 

Alex had to hold her breath to keep from breaking into hysterical laughter. Once she regained composure, Alex attempted to calmly say, “Wait, explain please.”

 

“Alex you were right about that evil space rock! Lena came over to CatCo for lunch again and we were having such a great time and as she was walking out I kinda yelled ‘Can we go out for dinner sometime this week?’ And she was like ‘Kara we always go out for food together hahaha of course.’ But then I was like ‘No I mean like go _out_.’ And at first she looked really shocked but then really happy and said she’d love to and now we have a date on Saturday. HELP,” Kara sputtered so fast that Alex could barely understand the garbled words.

 

“Okay just take a breath and we’ll figure this out. Don’t act weird around Lena and I’ll figure out how to reverse the effects okay?” Alex really had a difficult time keeping her voice even.

 

Kara whined into the phone, “But Alex–”

 

“Don’t worry, Kar. Just don’t hold anything back and we’ll get this sorted out,” Alex interrupted. Obviously her plan wouldn’t work if Kara actively stopped herself from spending time and flirting with Lena. The fake kryptonite was simply supposed to give her that boost of confidence to take a step forward with her feelings towards Lena.

 

Kara blew a raspberry then grumbled, “Fine. I’ll talk to you later.”

 

“Bye Kara. Good luck on your date.”

 

…

 

At around 10:00pm Saturday night, Kara burst through the DEO doors, “Alex! ALEX!! Oh Rao the rainbow kryptonite made me _kiss_ Lena. What am I going to do?! Y-you need to get it all out of me before–”

 

J’onn cleared his throat, “Alex, it’s been more than a few days.”

 

“Exactly!” Kara yelled, exasperated, “Why haven’t you figured out how to reverse it yet?”

 

J’onn, officially annoyed with Alex’s shenanigans, announced before she could respond, “Supergirl, there is no such thing as ‘rainbow kryptonite.’”

 

“W-what?”

 

“Oh man, she’s repressed,” Winn muttered under his breath, so Alex whacked him in the head. “Ow?!”

 

J’onn grumbled, “Your sister’s irresponsible usage of the placebo effect was meant to help you discover your natural sapphic propensity.”

 

Kara’s mouth opened and closed a few times, until she managed to stammer, “Then...then that means that I...wait...everything I have been feeling for Lena the past week was all me?” Her eyes widened, “I-I actually have real feelings for Lena?”

 

“Kara,” Alex began.

 

“You tricked me?” Kara furiously asked.

 

“Aaaand that’s our cue to leave,” Winn said, tugging J’onn away to give the Danvers sisters some privacy.

 

“How could you...Why didn’t you just talk to me?”

 

Alex rubbed her forehead, “Believe me, I tried for months. But you’ve been so incredibly dense.” Tears started glossing over Kara’s eyes. “Please, please don’t be upset. I know what I did was wrong, but I was just trying to help. Clearly you have these deep feelings for Lena that you just kept burying and I–”

 

Kara cut Alex off by rushing into her arms and squeezing tight. “Thank you,” she whispered. After a few sniffles, Kara continued, “I used to think that because you already liked women, it meant that I couldn’t. I don’t know where I got that ridiculous idea from. Society? Statistics? I have no clue.” She pulled away to look up at Alex, “What I do know, is that I think I fell in love with Lena months ago and I wouldn’t allow myself to feel it. I was so confused and scared and...Oh Alex, was this how you felt?”

 

Alex chuckled, “Yeah. It freaked me out.” Then she smiled down at her little sister, “But, I had yours and mom’s support and I had Maggie to help guide me through it. And that’s exactly what you’ve got: a whole team here to support you.”

 

Kara pulled away to smile appreciatively at Alex, “I think I need to go see Lena now.”

 

“Uh,” Alex tilted her head, “I’m pretty sure you shouldn’t tell her about the whole fake kryptonite thing, especially since she doesn’t even know you’re Supergirl.”

 

“Oh no, no! Of course not!” Kara laughed, “It’s just...after we kissed...I kinda screamed and ran straight here…”

 

“You did WHAT?!”

 

“Oh Rao Alex, I know that was so bad,” Kara panicked.

 

Alex sighed, “It’s okay, we can finish this discussion later. I think you need to get back to your girlfriend and do some reassuring, yeah?”

 

Kara’s cheeks flushed bright pink, “Yeah...Pizza night tomorrow?”

 

“Pizza night for sure,” Alex nodded, “Now as you once said to me: Go get the girl.”

 

“I will!” Kara beamed, “And now that I know rainbow kryptonite isn’t real, I can really kiss her Alex. Like really, _really_ kiss Lena!”

 

Alex raised an eyebrow, “Okay, TMI Kara…”

 

“Sorry,” Kara shyly bit her lower lip, then scampered out of the DEO and towards Lena’s apartment.

 

After she had a second alone, Alex grinned ear to ear. Honestly, Kara’s words weren’t a TMI; they were exactly what she wanted to hear and Alex couldn’t be more proud of her goofy little sister who’d finally realized she was head over cape in love with Lena.

**Author's Note:**

> Thanks for reading and I hope you enjoyed my fic :) 
> 
> Find me on tumblr @tht-lesbian-fangirl for any prompts, thoughts, etc.


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